Histological Processing of CAD/CAM Titanium Scaffold after Long-Term Failure in Cranioplasty.

Heilwig Fischer,Katharina Schmidt-Bleek,Carsten Rendenbach,Max Heiland,Jan-Dirk Raguse,Georg N Duda,Claudius Steffen

doi:10.3390/ma15030982

Abstract

Cranioplasty is a frequently performed procedure after craniectomy and includes several techniques with different materials. Due to high overall complication rates, alloplastic implants are removed in many cases. Lack of implant material osseointegration is often assumed as a reason for failure, but no study has proven this in cranioplasty. This study histologically evaluates the osteointegration of a computer-aided design and computer-aided manufacturing (CAD/CAM) titanium scaffold with an open mesh structure used for cranioplasty. A CAD/CAM titanium scaffold was removed due to late soft tissue complications 7.6 years after cranioplasty. The histological analyses involved the preparation of non-decalcified slices from the scaffold’s inner and outer sides as well as a light-microscopic evaluation, including the quantification of the bone that had formed over the years. Within the scaffold pores, vital connective tissue with both blood vessels and nerves was found. Exclusive bone formation only occurred at the edges of the implant, covering 0.21% of the skin-facing outer surface area. The inner scaffold surface, facing towards the brain, did not show any mineralization at all. Although conventional alloplastic materials for cranioplasty reduce surgery time and provide good esthetic results while mechanically protecting the underlying structures, a lack of adequate stimuli could explain the limited bone formation found. CAD/CAM porous titanium scaffolds alone insufficiently osseointegrate in such large bone defects of the skull. Future research should investigate alternative routes that enable long-term osteointegration in order to reduce complication rates after cranioplasty. Opportunities could be found in mechano-biologically optimized scaffolds, material modifications, surface coatings, or other routes to sustain bone formation.

Highlights

IntroductionTo ensure patient survival in the management of elevated intracranial pressure (ICP) or herniation syndrome, craniectomies are carried out hundreds of times a day worldwide as an indispensable part of therapy [1]
After cranioplasty are well known and failure risks and infection rates are Complications considered to be higher in autologous bone grafts than in alloplastic materials rates are considered to be higher in autologous bone grafts than in alloplastic materialsbone
Histological analyses of a removed individual porous computer-aided design and computer-aided manufacturing (CAD/CAM) titanium scaffold for skull reconstruction were performed for the first time

Summary

Introduction

To ensure patient survival in the management of elevated intracranial pressure (ICP) or herniation syndrome, craniectomies are carried out hundreds of times a day worldwide as an indispensable part of therapy [1]. After surviving the initial event, reconstruction of the skull defect is required after craniectomy to ensure physical protection of the underlying brain, to reestablish cerebral fluid dynamics, and to restore the shape of the skull in esthetic terms [2]. There are two main complications linked to the use of autologous bone that make the use of alloplastic material necessary, that is, bone resorption and infection [4]. The ideal cranioplasty material should fit the following criteria: achieve a complete closure of the defect, radiolucency, resistance to infections, heat and mechanical stability, easy shaping, and low costs

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Conclusion